DE10228594A1 - Production of colorless dibenzylamine - Google Patents

Abstract

The invention relates to a process for the preparation of colorless dibenzylamine by adding ammonium chlorides or amines to the technically obtained dibenzylamine and subsequent distillation.

Description

The invention relates to a new one Process for the preparation of colorless dibenzylamine by addition from ammonium chlorides or amines to the technically obtained dibenzylamine and subsequent distillation.

Process for the preparation of dibenzylamine in technical quality are known.

Dibenzylamine can be produced industrially from benzonitrile or benzamide by catalytic hydrogenation. Dibenzylamine can also be prepared industrially from benzonitrile or benzamide or from benzylamine or ammonia and benzaldehyde by reductive amination ( EP-A-644 177 ). Dibenzylamine can also be obtained as a by-product from the reaction of benzyl chloride with ammonia to give benzylamine (Ullmann, Benzylamine; Itsuno S, Koizumi T, Okumura C, Ito K, Synthesis, (2), p. 150-152, 1995).

Common to these procedures is that they usually use the educt in a solvent or diluent implement the mixed reaction mixture. Thereby to get the By-products, solvent and other by-products mostly separated by distillation. The dibenzylamine so obtained is colored, however.

Dibenzylamine in a color number after Hazen of more than 100 is so simple and easy according to the known ones Procedure accessible. However, if the aim is to produce colorless dibenzylamine, i.e. Dibenzylamine with a color number less than 100 is repeated Distillation necessary. The manufactured by the known methods Dibenzylamine has a low stability and decomposes easily under discoloration.

Dibenzylamine can e.g. used become stabilizers for Manufacture plastics. discoloration are not wanted here.

The invention was based on the requirement a process for the preparation of colorless dibenzylamine and avoiding repeated distillation. The dibenzylamine obtained should have a high stability.

There has been a manufacturing process of colorless dibenzylamine with a color number of less than 100 Hazen found, which is characterized by an additive from the group of ammonium chlorides or amines to be cleaned Dibenzylamine added and the mixture is then distilled.

The colorless dibenzylamine thus prepared has high stability on.

Ammonium chlorides for the process according to the invention correspond to the following formula: R ¹ R ² R ³ N-HCl in which
R ¹ , R ² and R ³ , independently of one another, denote H or an organic radical.

The organic residue is / are C1-C6 aliphatic or to understand benzyl. Benzyl groups or are preferred H.

Very particularly preferably from the The group of ammonium chlorides is ammonium chloride or a mixture the benzyl / dibenzylamine hydrochloride.

Examples are ammonium chlorides such as hydrochloride, ammonium chloride or its relatives or also aqueous or anhydrous hydrochloric acid and benzyl chloride. A mixture of the benzyl / dibenzylamine hydrochlorides is / are preferred. Ammonium chloride is very particularly preferred.

Amines are to be understood as those their volatility is low so that they remain almost completely in the distillation residue. Examples of amines for the inventive method are high-boiling amines such as tetraethylene pentamine (TEPA), distillation residues from Tetraethylene pentamine (TEPA), hexaethylene heptamine (HEHA), and pentaethylene hexamine (PEHA) their mixtures or mixtures with higher or lower boiling ones Analog.

Within the scope of the present invention is understood by "high-boiling Amines "such amines, which boil higher than dibenzylamine under the respective conditions.

The ammonium chlorides and Amines are known per se in terms of their chemical composition and available as commercial products. Pentaethylene hexamine (PEHA) and distillation residues of Tetraethylene pentamine (TEPA) used, very particularly preferred Pentaethylene hexamine (PEHA).

Amines also include polyamines understand. Polyamines are understood to mean those compounds that from a saturated Hydrocarbon chain with terminal Amine functions, interrupted by a changing number of secondary and / or tertiary and / or quaternary Amino functions exist.

Polyamines are preferred in the inventive method used, selected from the group of the reaction products of dichloroethane with ammonia and / or other amines or from the group of the reaction products from ethylene oxide with ammonia or other amines. These products are usually water-soluble / water-miscible liquids or solid hydrates.

Polyamines in which the polyamine corresponds to one of the following formulas (II) or (II) are very particularly preferred: H _p N (CH ₂ -CH ₂ ) _q - [NH _r (CH ₂ -CH ₂ ) _S ] _n -NH _t (I) NH ₂ -CH ₂ -CH ₂ -CH ₂ - [NH _r - (CH ₂ -CH ₂ -CH ₂ ) _S ] _n -NH _t (II) where "n" represents 0 or an integer from 0 to 300,
p, q, s and t stand for 1 and / or 2, and
r represents 0 or 1.

These amines can be used as free amine or as a salt, preferably as chloride.

They can also be cross-linked by other reagents or be branched, e.g. B. by subsequent reactions with dichloroethane, Ethyleneimine or acrylonitrile, possibly with subsequent reduction.

Compounds from the group of ammonium chlorides or amines can according to the invention as additives be used.

The additive becomes the one to be cleaned Dibenzylamine in a concentration of 0.01 to 15 wt .-%, preferred in a concentration of 0.1 to 3% by weight, based on dibenzylamine, added.

The distillation of the to be cleaned Dibenzylamine is preferably controlled so that a bottom temperature from 120 to 220 ° C, preferably from 160 to 200 ° C is achieved. The pressure is preferably set so that the mixture boils under the temperature conditions. After one colored The product is pure dibenzylamine with a color number of <100 Hazen won.

The color number of 100 Hazen is thus safe to fall below. I.d.R. products with a color number <30 Hazen (colorless), often also color numbers <10 Hazen observed.

Within the scope of the present invention one understands by color number one determined under fixed conditions Characteristic value for the color of transparent substances by optical comparison is detected. This can be by comparison with color charts according to standard, e.g. according to DIN EN 1557 (March 1997) or determine by comparison with standardized solutions.

To stabilize the pure dibenzylamine stored it under nitrogen. In addition to nitrogen, one can Addition of hydrazine (aqueous or anhydrous) or hydroxylamine (aqueous or anhydrous) Storage time with unchanged and only slightly modified Increase color number significantly. The additives hydrazine and hydroxylamine are used individually or as a mixture in concentrations of 0.01 to 10.0% by weight on the pure dibenzylamine.

The inventive method is intended to following examples explained become; Percentages are percentages by weight.

example

591 g of a side stream from the Production of benzylamine, containing 0.1% water, 18% benzylamine, 0.5% benzyl alcohol, 77.9% dibenzylamine and 0.7 benzalbenzylamine as well as approx. 3% of other components is mixed with 2.2 g ammonium chloride and 7.5 g of pentaethylene hexamine are added and heated to 200 ° C.

After fractional distillation receives 423 g (92% of theory) of dibenzylamine of the color number 11 Hazen with a Purity of 99.74%. The color number was here by a device from the company Dr. Long in Düsseldorf determined according to DIN EN 1557.

The product is under nitrogen with hydroxylamine (0.04%) and is stable in storage. A storage at 60 ° C for 28 Days changed the color number to 30 Hazen. Without hydroxylamine as a stabilizer changes the color number after 28 days to 90 Hazen.

Claims (12)

A process for the preparation of colorless dibenzylamine with a color number of less than 100 Hazen, characterized in that an additive from the group of ammonium chlorides or amines is added to the dibenzylamine to be purified and the mixture is then distilled. A method according to claim 1, characterized in that the ammonium chloride corresponds to the following formula: R ¹ R ² R ³ N-HCl, wherein R ¹ , R ² and R ³ independently of one another are H or an organic radical, and the organic radical is C ₁ -C ₆ -aliphates or benzyl. Method according to claims 1 and 2, characterized in that the ammonium chloride is benzyl chloride, a hydrochloride, ammonium chloride or its relatives or aqueous or anhydrous hydrochloric acid, in particular ammonium chloride or a mixture of the benzyl / dibenzylamine hydrochlorides is. Method according to claim 1, characterized in that the amine boils higher than dibenzylamine. Method according to claims 1 and 3, characterized in that the amine tetraethylene pentamine, distillation residues of Tetraethylene pentamine, hexaethylene heptamine or pentaethylene hexamine, especially pentaethylene hexamine. Method according to claim 1, characterized in that the amine is a polyamine from the group the reaction products of dichloroethane with ammonia and / or others Amines or from the group of reaction products from ethylene oxide with ammonia or other amines. A method according to claim 1, characterized in that the amine corresponds to one of the following formulas (I) or (III): H _p -N (CH ₂ -CH ₂ ) _q - [NH _r - (CH ₂ -CH ₂ ) _S ] _t (I) NH ₂ -CH ₂ -CH ₂ -CH ₂ - [NH _r - (CH ₂ -CH ₂ -CH ₂ ) _S ] _n -NH _t (II) where "n" stands for 0 or an integer from 0 to 300, p, q, s and t stand for 1 and / or 2 and r stands for 0 or 1, whereby the amine can be present as a free amine or as a salt. Method according to claims 1 to 7, characterized in that the addition of the dibenzylamine to be purified in a concentration of 0.01 to 15 wt .-%, in particular of 0.1 to 3% by weight, based on dibenzylamine, is added. A method according to claims 1, characterized characterized in that the distillation of the dibenzylamine to be purified a bottom temperature of 120 to 220 ° C, in particular from 160 to Has 200 ° C, and that the pressure is adjusted so that the mixture under the Temperature conditions boils. Method according to claims 1 to 8, characterized in that the pure Diebenzylamin under nitrogen is stabilized. A method according to claims 9, characterized characterized in that the pure dibenzylamine also by adding aqueous or anhydrous hydrazine or aqueous or anhydrous hydroxylamine is stabilized. Method according to claim 10, characterized in that the hydrazine or the hydroxylamine individually or as a mixture in concentrations of 0.01 to 10% by weight is added to the pure, light-colored dibenzylamine.